Underreamer



July 16, 1929.

A. B. EDWARDS 1,720,950

UNDERREAMER Filed Dad. 22, 1927 Patented July 16, 1929.

UNETED- STATE-S PATENT, :OFFICE.

ALBERT B. EDWARDS, or vnn'ruaa, carmoimm. issrexo'n 'ro Joan LOS enemas, (man-omen.

UNDEBB-EAMEB.

Application filed. December 22, 1987. Serial No. 241,981.

This invention relates enerally to underreamers such as are used in underreaming or enlarging a drilled well hole below the well pipe; either to enlarge the hole to a size larger than. the exterior diameter of the pipes and its collars, or to a size larger than is drilled by a bit which i s lowered through the well pipe. 1

The principal objects of this invention are generally to improve upon and simplify the construction of existing forms of deep 'well underrcamers, and, to provide simple and efiicient means for expanding the cutters outwardly into reaming position. It is also an object to provide an arrangement whereby the cutters are locked in their contracted positions.

One of the characteristic features of the invention resides in its employment of both relative rotation and relative longitudinal movement between the cutters and the mandrel. Specifically, as in the illustrative embodiment ofthe accompanying drawings, the

cutters are mounted in asurrounding cageor tubular body which is provided with vertic-ally extending slots, the cutters being vertically movable in those slots with relation to the body, the body being verticall immovable with relation to the interior'mandrel which is secured to the lower end of the drill stem. The mandrel is relatively rotatable inside the body and within the cutters; and the structure is such that expansive movement of the cutters is caused by relative rotation while contractive movement is caused by relative longitudinal. movement (relative downward movement of the cutters on the mandrel), And when the cutters move downwardly on the mandrel they can move in under downwardly facing mandrel shoulders so that then the cutter raising spring presses them up against those shoulders and locks them in their 'contra'ct'ive positions.

With the foregoing and other objects .in

the bits or cutters in their extended positions. or in the positions they assume when cutting or reaming.

Fig. 2 is an elevational view partly insec- GBANT, Or

tion of the underreamer and showing the bits or cutters in retracted position.

Fig. 3 is a horizontal section taken on the line 3-3, of Fig. 1.

Fig. 4 is a horizontal section taken on the line 4 4, of Fig. 1.

Fig. 5 is a horizontal section taken on the line 5-5, of Fig. 2.

Fig. 6 is a horizontal section-taken on the line 66, of Fig. 1;

Referring by numerals'to the accompanying drawings, which illustrate a practical embodiment of my invention,10 designates a cylindrical member that forms the body or hit carrying cage of the underreamer, saidbody being provided with an axially disposed bore 11 for the accommodation of the mandrel and other parts of the underreamer, andthe lower portion of the bore 11' is reduced in diameter as designated by 11*,

thereby forming within the lower portion of .the cage or body an annular shoulder 12.

The lower end of the body 10 is internally threaded as designated by 13 for the reception of a coupling member or the threaded tool-joint pin of the drill, shank, and connccting the threaded recess at the lower end of the body with the'lower end of the chamber 11 -isan axially disposed circulation opening 14.

In the Wall of the body or cage 10 is a series of radially-arranged longitudinally ex.

tending slots 15 for the accommodation of the bits or cutters and there may be any convenient number of these slots, although for practical purposes I find that an underreamer having three slots and cutters meets requirements.

' Occupying the bore 11 within the body or cage 10 is a substantially cylindrical mandrel 16, the lower portion of which terminates within the reduced bore 11 in the lower portion of body 10, and formed through said mandrel is an axially disposed bore 17 which together with the opening 14 constitutes a .circulation duct through which mud or water is circulated While the bit and underreamer are in operation. The upper end of the mandrel 16 has a threaded tool joint box} 18 for the reception of the corresponding pm of a coupling that connects the underreamer to the drill pipe.

Formed on the mandrel a short distance below its upper end is a series of three radially disposed and equidistantly spaced lugs 19, and which lugs project into arcuate slots 20 that are formed in the upper portion of the body 10. That portion of the body 10 above the slots 20 is internally threaded to receive the threaded portion of a collar 21, which latter encircles the upper portion of the body of the mandrel 16 and retains the body and mandrel in assembled relation while allowing the limited relative rotation hereinafter described.

The slots 20 are approximately 90 in length and the lugs 19 are approximately 30 in length, therefore the body and mandrel are capable of being moved approximately or one-sixth of a turn relative to each other.

Formed on the mandrel below the lugs 19 and arranged at different elevations are two sets of horizontally disposed eccentric faces 22, and formed on the mandrel just below each set of these eccentric faces is an annular shoulder 23 which are, in effect, the

lower surfaces of the cams.

Positioned in the radial slots 15 are bits or cutters 24:, the length thereof being somewhat less than the length of said slots, and formed on the side faces of these bits or cutters adjacent to their inner edges are shoulders 25, which are adapted to engage against the face of the body wall thus limitin the outward movement of the cutter relative to the body or cage. portions of the inner edges of the bits or cutters 24 are notched or cut away as designated by 26, and those portions of the inner edges above and below the cut away portions or notches 26 normally engage on the eccentric faces 22 of the mandrel. Arranged to slide vertically upon the lower portion of the mandrel and within the lower portion of the bore 11 in body 10 is a hollow ring or collar 27 and interposed between this, ring or collar and the shoulder 12 at the lower end of chamber 11 is an expansive coil spring 28 which normally exerts upward pressure on the ring or collar and upon the bits or cutters.

That portion of the mandrel 16 that proects into the bore ll 'of reduced diameter is reduced in diameter and arranged thereon is a packlng ring or collar 29 which is effective in preventing mud and water from passing upward through the joint between the lower portion of the mandrel and the body or cage.

Before lowering the underreamer into a well that is to be reamed, the cutters 24 are set in retracted positions with their inner edges positioned against the low portions of The intermediate the eccentric faces 22, and the underreamer carried by the drill pipe is now lowered thru the casing to the point in the open hole that is to be enlarged; In this relative position, the cutters are up, as shown in Fig. 1, and bear inwardly against the low portions of the eccentric faces. I I

Upon rotating the drill pipe toward the right hand, the mandrel 16 will be rotated approximately one sixth of a turn, thereby moving the high portions 'of the eccentric faces into position beneath the cutters and moving the same outwardly to their limit of movement, as illustrated in Figs. 1 and 4.

The underrean'ier is now in cutting position and as the drill pipe is rotated, the outer edges of the cutters will engage and cut away the formation, thus accomplishing the reaming operation.

lVhen it is desired to retract the cutters this may be done by rotating the mandrel left-handedly, so as to bring the lower or narrower parts of the cams back to the relative rotational position they previously occupied when the contracted tool was put' down through the pipe, the cutters still occupying their upper positions. Left handed rotation of the drill stem, however, is usually undesir-able; and the reamer may be contracted by pulling it directly upwardly, the cutters 2& coming into contact with the casing or casing shoe and thus being pushed relatively.

downwardly on the mandrel, against the actionof spring 28. The upper outer corners of the cutters are rounded or beveled as at 24, so that. as the cutters are pushed down they are also pushed inwardly by the lower end of the casingor casing shoe; and thus when the cutters have been pushed down to the relative elevation shown in Fig. 2 they will then be pushed inwardly so that the upper inner corner of each cutter and the upper face of the lower lug of each cutter, will be pushed in under the downwardly facing shoulders 23. The mandrel cams, in the meantime, have not been rotated, so that the cutters are thus pushed inwardly under the higher or wider parts of the cams. The cutters then occupy substantially the positions shown in Figs. 2 and 5, except that the higher or wider parts ofthe cams are opposite and overhang them. Spring 28 then acts to hold the cutters upwardly against the shoulders 23, and the friction of the cutter engagements with those shoulders 23 is sufficient to effectually hold the cutters in collapsed p01 sition and prevent them from moving out to ride against the casing as the tool is being withdrawn.

Then when the tool reaches the surface it can be put back into its original contracted position, by rotating the mandrel relatively left handedly (or, which amounts to the same thing, by rotating the body and cutters relatively right handedly about the mandrel) until the lower or narrower parts of the cams are above the cutters. Then a comparatively slight outward movement of the 1 cutters will allow them to ride upwardly on tion and" an upper contracted position.

- normally From the upper contracted position the cutters are thrown to their expanded position by relative rotation; and the cutters are moved from their upper expanded positions to their lower contracted positions by relative longitudinal movement.

Thus it will be seen that I have provided an undrreamer that is relatively simple in construction, inexpensive of manufacture and in which the bits or cutters may be readily and positively projected from the body or cage and likewise retracted and locked in such retracted position, and the projection and retraction of the bits or cutters being effected with comparatively little relative movement between the body or cage of the underreamer and the mandrel forming a part thereof.

alt will be readily understood that minor changes in the size, form and construction of the various parts oiour improved well drilling apparatus may be made and substituted for those herein shown and described; without departing from the spirit of my invention, the scope of which is set forth in the appended claims.

I claim as my invention 2- 1. In an underreamer, a cage provided with a plurality of slots, bits arranged for movement within said slots, a mandrel extending through said cage and mounted for limited rotary movement relative thereto,

said mandrel being provided with eccentric shoulders for engagement with the inner edges of the bits, and shoulders formed on said mandrel beneath which the bits are adapted to engage when in retracted positions."

2. In an u'nderreamer, a cage provided with a pluralityof slots, bits arranged for.-

movement within said slots, a mandrel extending through said cage and mounted for limited rotary movement relative thereto, said mandrel being ,provided with eccentric shoulders for engagement with theinner'. edges of the bits, shoulders formed on said mandrel beneath which the bits are adapted to engage when in retracted positions, and yielding pressure means within the cage for exerting upward pressure against said bits.

V In an *underreamer, a cage provided with a plurality of slots. bits arranged for movement within said slots, a mandrel extending through said cage and mounted for limited rotary movement relative thereto, said mandrel being provided with eccentric shoulders for engagement with the inner edges of the bits, shoulders formed on said mandrel beneath which the bits are adapted to engage when in retracted positions, and said mandrel and cage being provided with alined circulation ducts.

4. In an underreamer, a cage provided with a plurality of slots, bits arranged to move vertically and radially through said slots, a mandrel associated with said cage, eccentric faces formed on said mandrel for engagement with the inner edges of said bits, and means on said mandrel and bits for locking the latter against vertical movement when in retracted positions.

5. In an underreamer, a cage provided with a plurality of slots, bits arranged to move, vertically and radially through said slots, a mandrel associated with said cage, eccentric faces formed on said mandrel for engagement with the inner edges of said bits, means on said mandrel and bits for locking the latter against vertical. movement when in retracted positions, and yielding pressure means arranged -within said cage beneath said bits.

6. In an underreamer, a cage provided with a plurality of slots, bits arranged for vertical and radial movement through said slots, a mandrel extending into said cage and arranged to rotate for a limited degree and projecting said bits when said mandrel is rotated, and means on said mandrel and bits for locking the latter in retracted positions.

7. In an underreamer, a cage provided with a plurality of slots, bits arranged for vertical and radial movement through said slots, a mandrel extending into said cage and arranged torotate for a limited degree there1n,-means on said mandrel for engaging and. projecting said bits when said mandrel is rotated, means on said mandrel and bits for locking the latter in retracted positions, and yielding pressure means arranged within the cagebeneath said bits.

8. In an underreamer, a cage provided with a plurality of slots, bits arranged for vertical and radial movement within said slots, a mandrel extending into said cage between said bits and having a limited degree of rotary movement relative to said cage, and means on said mandrel and bits whereby the latter are projected upon rotary movement of said mandrel and whereby said bits are locked against vertical movement when retracted.

9. In an underreamer, a cage provided with a plurality of slots, bits arranged for vertical and radial movement within'said slots, a mandrel extending into said cage between said bits and having a limited degree latter are projected upon rotary movement 7 of said mandrel and whereby said bits are locked against vertical movement when retracted, and yielding pressure means within thescage beneath said bits.

10. In an underreamer, a cage provided with a plurality of slots, bits arranged for vertical and radial movement within said slots, a mandrel extending into said cage between said bits and having a limited degree of rotary movement relative to said cage, means on said mandrel and bits whereby the latter are projected upon rotary movement of said mandrel and whereby said bits are locked against vertical movement when retracted, yielding pressure means within the cage beneath said bits, and said mandrel and cage being provided with circulation ducts.

11. In an underreamer, a cutter-carrying cage, cutters arranged for vertical and radial movement in and with relation to said cage, a mandrel extending into said cage between the cutters and having rotary movement with relation to the cutters, and means on said mandrel and cutters whereby the cutters are projected upon rotary movement of the mandrel and whereby the cutters are locked against vertical movement when retracted.

12. In an underreamer, a cutter-carrying cage, cutters arranged for vertical and radial movement in and with relation to said cage, a mandrel extending into said cage between the cutters and having rotary movement with relation to the cutters, means on said mandrel for projecting said cutters when said mandrel is rotated, and means on said mandrel and cutters for locking the cutters in retracted position.

13. In anunderreamer, a cutter carrying cage, cutters arranged for vertical and radial movement within and with relation to said cage, a mandrel extending into said cage between the cutters and rotatable with relation to the cutters, the mandrel having thereon a radial cam of limited longitudinal extent along the mandrel and whereby relative rotation of the mandrel causes outward projection of the cutters, and the mandrel also having a downwardly facing shoulder under which the cutters are adapted to be brought by relative downward longitudinal and inward movement of the cutters.

14. In an underreamer, a cutter carrying cage, cutters arranged'for vertical and radial movement within and with relation to said cage, amandrel extending into said tive rotation of the mandrel causes outward projection of the cutters, and yielding means urging the cutters upwardly longitudinally of the mandrel and cage.

15. In an underreamer, a cutter carrying cage, cutters arranged for vertical and radial movement within and with relation to said cage, a mandrel extending into said cage between the cutters and rotatable with relation to the cutters, the mandrel having thereona radial cam of limited longitudinal extent along the mandrel and whereby relative rotation of the mandrel causes outward projection of the cutters, and said cam having at its lower end a downwardly facing shoulderunder which the cutter is adapted to be moved by relative longitudinal downward and inward movement of the mandrel.

16. In an underreamer, a cutter carrying cage, cutters arranged for vertical and radial movement within and with relation to said cage, a mandrel extending into said cage between the cutters and rotatable with relation to the cutters, the mandrel having thereon a radial cam of limited longitudinal extent along the mandrel and whereby relative rotation of the mandrel causes outward projection of the cutters, said cam having at its lower end a downwardly facing shoulder under which the cutter is adapted to be moved by relative longitudinal downward and inward movement on the mandrel, and yielding means urging the cutters longitudinally upwardly on the mandrel.

17. In an underreamer, a cutter carrying cage, cutters arranged for vertical and 'radial movement within and with relation to said cage, a mandrel extending into said cage, between the cutters and rotatable with relation to the cutters, the mandrel having thereon a radial cam of limited longitudinal extent along the mandrel and whereby relative rotation of the mandrel causes outward projection of the cutters, said cam projecting outwardly beyond the surface of the mandrel immediately below the cam, whereby relative downward longitudinal movement of the cutters on the mandrel causes the cutters to disengage the cam. V

18. In an underreamer, a cutter carrying cage, cutters arranged for vertical and radial-movement within and with relation to said cage, a mandrel extending into said cage between the cutters and rotatable with relation to the cutters, the mandrel having thereon a radial cam of limited longitudinal extent along the mandrel and whereby relative rotation of the mandrel'causes outward projection of the cutters, said cam projecting outwardly beyond the surface of the mandrel immediately below the cam, wherement of the cutters on the mandrel causes the cutters to disengage the cam and yielding means urging the cutters longitudinally upwardly on the mandrel.

'by relative downward longitudinal move- 19. In an underrea-mer, a cutter carrying cage, cutters arranged for vertical and redial movement Within and with relation to said cage, a. mandrel extending into said cage betweenthe cutters and having rota,- tive movement relative to the cutters, it

downwardly facing shoulder on the mandrel and of limited circumferential extent about the mandrel, the cutters inone position adapted to rest under said shoulder, and 10 said shoulder adapted to be carried out of cutter-engaging position by relative rotation of the mandrel.

In testimony whereof I afiix my signature.

ALBERT B. EDWARDS. 

